Note: This is a monthly feature published by ChannelAdvisor highlighting the Same Store Sales (SSS) across our wide range of over 3000 retailers and ~$3.5b in GMV. Details on the SSS including methodology and schedule can be found in this...

Note: This is a monthly feature published by ChannelAdvisor highlighting the Same Store Sales (SSS) across our wide range of over 3000 retailers and ~$3.5b in GMV. Details on the SSS including methodology and schedule can be found in this post. If you are interested in last month's (November 2011) results you can find them here.

Today we are releasing December data for Marketplaces (eBay/Amazon), Search and Comparison Shopping Engines (CSE). Also as this is the last of the SSS data for 2011, we provide some closing Holiday/2011 thoughts.

Later in January we will be posting the 2012 SSS schedule as well as detailing any changes.

December 2011 results

December is the end of the Holiday period and gives us our last insights into how the Holiday shaped up for e-commerce until we see public reports from retailers, Google, eBay and Amazon.

Here are the highlights from December 2011's SSS:

Overall - Overall December came in at up 21% - a steady showing on top of November's robust 25% This puts to bed the bear case that Holiday 2011 (at least for e-commerce) was front-end loaded.

Amazon - Amazon came in at 51.3% continuing their share-gains in e-commerce. This is down slightly from November's 60% growth rate. As we've mentioned previously what we think is going on is that Amazon is being more competitive and deeper at the product level and that's giving 3P sales a slight headwind and also last year's comp is very tough. Amazon did issue a press release that was mostly Kindle oriented, but did also feature some interesting stats about 3P. You can read the complete release here. My favorite piece was this excerpt: "the number of sellers who exceeded $5,000 in sales during the holiday season increased 44 percent year-over-year. For the year, businesses on Amazon sold hundreds of millions of units worth billions of dollars worldwide."

eBay - eBay's growth accelerated nicely again in December, coming in at 22.1%. Note that this is the fastest pace we recorded in 2011 and since we began releasing SSS data @ ChannelAdvisor. We expect a lot of questions around this datapoint so have provided copious eBay details further in the report.

Search - Search finished a great year coming in at 18.1% for December.

CSE - Comparison Shopping Engines continued their 2011 struggles with another weak month coming in at down 1.8% year over year.

SSS Chart

The following chart details the SSS data for December 2010 through December 2011: (click to enlarge)

eBay Observations

Early in the report we highlighted that eBay had it's strongest showing since we started tracking SSS with a 22.1% y/y increase. Not only is this a record, but eBay is now growing a tad faster than e-commerce overall for us and you can visually see from the chart above they appear to be closing the gap with Amazon's growth rate a bit.

Before digging into what's behind this surge in growth at eBay, here are a couple of interior datapoints of interest.

eBay Motors Parts and Accessories - This category saw very strong growth in December, coming in at a record-setting 57.6% y/y growth for ChannelAdvisor customers in the category. This is highly unusual as usually growth in the category wanes in the Winter months. We've said there is probably some warmer than usual weather benefit here, but frankly this seems to be a category where eBay is really hitting on all cylinders and bodes well for the focus on other verticals like Fashion and CE.

Auctions - Auctions continue to drag on eBay's growth rate showing a decline of 18% y/y. But for ChannelAdvisor customers Auctions are now a small enough percentage they are not diluting the growth as the did. It's important to note that ChannelAdvisor's customers have been ahead of the format change compared to the data that eBay reports and eBay's overall growth rate could be much lower as they have a higher concentration of auctions than our seller base.

Fixed-price - Fixed Price transactions grew at 26.8%

Large Merchants - The HP/Touchpad sale and several other sales by large merchants at the end of the holiday season

Holiday 11 - While no 'one' hot item was written about much this holiday, there were a good 10-20 toys across genders and age groups that were very thin and traded vigorously on eBay.

Given that data we believe the top five contributors to eBay's stellar December results were:

Large merchants - We're a bit biased on this as most of these merchants are customers, but even those that are not (like buy.com) are turning in record numbers (buy.com cracked $6m/m for the first time in Dec.) - eBay buyers clearly like the availability of this type of inventory and are voting with their wallets.

eBay Motors P+A - Congrats to the Motors team for turning in a great December, Q4 and frankly 2011. This category is clearly on fire and with tons of enhancements to the buying experience over the year, the team kept the fanning the flames. eBay also had a great presence at SEMA which could have played a role and tees up a great 2011. It will be exciting to see what further innovations eBay has for this category in 2012.

Hot toys, hard to find - Items like LeapPad, Monster High, Paper Jams and lots of other toys were sold out at retail by BlackFriday. eBay benefited substantially from this in December. Even iPhone 4S' were hard to find!

Back-end loaded - Last year we saw the holiday pull up - indicating that shoppers started early - and stopped by about 12/7. This year they were either procrastinating, having a hard time deciding, spending more or dipping into their credit cards. Or perhaps they were disenfranchised with the offline shopping experience. Whatever the underlying reason, eBay definitely benefited from more activity in December over-all than we saw last year.

It's important to restate here our normal disclaimers that ChannelAdvisor's data is not a perfect proxy for eBay:

Our customers are larger than the eBay average

We have different category mix

We have different geography mix

Our customers tend to be ahead of the FP/Auction format transition

Search Details and Observations

Here are the search details for December 2011:

Note that CPC was down y/y and conversions were way up - this is primarily due to the bulk of our customers this year being in the Product Listing Ads (PLA) system whereas last year it was in limited beta. This program is nirvana for retailers as it drives higher conversions at lower CPCs and is also a win for Google as the absolute revenue is substantially increased because of the increase in efficacy.Also note that AOV this year is essentially identical to last year which indicates that consumers continue to buy items in the same price-range. Historically in 2008 for example during the Great Recession, we saw this drop precipitously as consumers significantly pulled back.Holiday 2011 WrapIn our late December report we concluded that the holiday came in ~23% up y/y for our customers on a SSS basis. December's final report solidifies this datapoint. The 23% is significantly above our 17% forecast - hopefully these trends continue into 2012.Happy New Year everyone! We'll be back shortly with 2012's schedule and our normal blogging pace.SeekingAlpha disclosure - I am long Google and Amazon. eBay is an investor in ChannelAdvisor where I am CEO.